textproduct: Rapid City

KEY MESSAGES

-Near average temperatures through the weekend with highs mainly in the 70s

-Another lobe of tropical moisture expected early next week, supporting more chances for rain Sunday and Monday

-Slightly cooler next week

DISCUSSION

(This Afternoon Through Thursday) Issued at 1144 AM MDT Fri Sep 25 2026

Upper trough will remain in place through early next week over the western CONUS, supporting mainly WSW flow aloft. Pattern change expected toward next weekend as a strong NE Pac upper trough dives into the Pac NW and supports a couple stronger upper troughs and associated sfc low's across southern Canada and the northern CONUS. Lingering monsoon wave will phase with a stronger upper trough moving across southern Canada today into Sat. Enough diurnal instability will be in place to support isolated to scattered showers/storms in the SW FA. However, the better chances for rain will be to the east of the FA where deeper moisture is in place. Associated cool front will move through Sat with breezy NW winds developing over western SD for a bit. Drier air will move into the region, supporting dry weather through most of Sunday before the next upper trough and batch of tropical moisture advects into the region. Upper trough will drop into the SW CONUS Sunday and direct tropical moisture NE across the Rockies. The path of this moisture and the location of best forcing is still not settled in forecast models and will hinge on the upper closed low's track, which are difficult to predict for forecast models. Hence, rain chances are likely to change in the next few model cycles. The best window for rain will be Sunday night into Monday, with things drying out after. Slightly cooler, but seasonal the rest of the week. Models are still indicating a stronger cold front next weekend, which could bring a widespread frost as the upper trough over the NE Pac shifts east and forces cold air south out of Canada. However, the degree of CAA with this system varies substantially among the various forecast models and ensembles.

AVIATION

(For the 18Z TAFS Through 18Z Saturday) Issued At 1146 AM MDT Fri Sep 25 2026

VFR conditions are expected for northeast Wyoming and far western South Dakota through the TAF period. An isolated showers/thunderstorms cannot be ruled out for parts of northeast Wyoming and southwest South Dakota this afternoon into the early evening. Low clouds will stick around south-central South Dakota throughout the day before expanding west into parts of northwest and southwest South Dakota during the overnight hours. Patchy fog may lead to IFR/LIFR conditions across portions of the South Dakota plains Saturday morning. Conditions will improve west to east, with most areas returning to VFR by the end of the TAF period.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.